Fibrous carpet and/or rug are nowadays used broadly for flooring materials. Most of these materials consist of synthetic polymeric compounds, with other high end materials by natural materials such as wool and silk, etc. The United States carpet and rug industry consumes nearly 50% of the total global production; among these about half are nylon based materials. Due to the fact that both manufacturing and coloring/imaging flooring material involved energy and chemicals, effective use of energy and materials is of a great consideration of the impact toward environment.
Commonly, three different coloring methods are used to bring colors and/or images to fibrous type of flooring materials: wet dyeing, solution dyeing and color printing including monochromatic printing. Among these, wet dyeing and printing are more often used because they are more suitable for a variety of color requirements and images. Moreover, the printing process can be operated at an on-demand therefore substantially decrease the inventory burden.
Screen printing such as flatbed screen printing, either manual or automatic process, is the major and common technique for fibrous flooring material imaging. A pre-made screen with carefully selected and oriented dithering small holes is to be used by mechanically processing color paste through these tiny holes onto the surface of the flooring material producing various color patterns. The process bears disadvantages of long preparation time and high short run cost. If more than one color needed, multiple steps of making screens and overlapping of these color pastes are to be used.
In recent years, digitally controlled color paste discharging or jetting techniques are used to generate color images making flooring materials. Examples of these mechanical jetting or discharging techniques include ChromaJet® and Millitron® injection dyeing for carpet and rugs. Both techniques, however, suffer from the fact that high viscosity ‘inks’ are used, with excessive amount of colorants and gels. As a result, in addition to the fixing or curing energy needs, excessive amount of water and energy are required for washing away the oversaturated and un-reacted colorants. As much of 10 to 15 gallons water consumption and waste water treatment are associated in producing carpet/rugs associated with the above imaging methods. Furthermore, these mechanical jetting techniques typically suffer from low printing resolution of less than 100 dot-per-inch (DPI) and may not satisfy photographic image needs for high quality image applications.
Chemicals and volatile organic compound (VOC) from the high viscosity paste oversaturated dyeing or printing often are released into the environment. For instance, unreacted benzidine-based azo dyes are considered to be carcinogenic. Plastisol compounds discharged into water systems may pollute environment permanently. Large quantity of salt, often from excessive amount of acid/based neutralization as a result of high viscosity pasted technique, is also a huge problem for waste water treatment. Heavy machinery needs for the washing process is also a burden from cost-effective consideration.
A need exists to produce fibrous flooring materials, with high resolution color imaging without creating, or reducing, environmental or energy burdens.